This invention relates to folding machines; and, more particularly, to a mechanism for adjusting the spacing between fold-rollers thereof.
A preferred form of the invention is embodied in a buckle-type folder. In this respect, a conventional buckle folder is schematically illustrated in FIG. 1 of the drawings. Therein, a fixed roller, or roll, F has five relatively movable or "floating" rollers associated therewith. That is, all of the rollers are journalled in a frame, not shown, but roller a is pivotably adjustable about point 10 by an adjusting means schematically illustrated as 12 in order to adjust a first "nip" space indicated by arrow 1. Roller b is similarly adjustable with respect to the fixed roller F in order to adjust the "nip" space indicated by arrow 2; roller c is adjustable with respect to roller b in order to adjust the nip space indicated by arrow 3; roller d is adjustable with respect to roller c in order to adjust the nip space indicated by arrow 4; and so on.
It should be noted, with respect to the above described conventional folder, that since only roller F is fixed, errors in adjusting subsequent rollers are culmulative.
In operation, when a sheet of paper, such as P in FIG. 1, is to be folded it is fed between the fixed roller and the first roller a until it strikes a stop S in a first fold pan 14. The paper then buckles downwardly as shown at P-2 into the "nip" illustrated by arrow 2 between the fixed roller F and the second movable roller b. The paper is then fed and buckled in seriatim into fold pan 16; between movable rollers b and c; into fold pan 18; between movable rollers c and d; and so on.
From the above description, it can be seen that the sheet P is folded over and over again so that the stock thickness passing between successive rollers gets larger and larger. In this respect, each of the movable rolls b-e is conventionally separately adjustable by a lever and spring arrangement similar to the structure such as 12 associated with the first movable roller a; and, moreover, each movable roll has a similar lever-spring structure located on each of its ends. Additionally, it should be noted that adjustment of one of the movable rollers such as b, in order to change the nip space indicated by arrow 2, conventionally results in an alteration of a nip space indicated by arrow 3 and so on.
Finally, before turning to the structure of the invention, it should be appreciated that the various rollers are conventionally gear-driven. Since the position of each of the movable rollers is dependent upon another, however, the customary gear train between the rollers cannot satisfactorily drive or be driven on their "pitch diameters." Hence, not only is there a resulting loss in efficiency, but the gears run quite noisily; and, the drive-power requirements become disproportionately larger with each additional movable roller that is added to the train.
It is a fundamental purpose of the instant invention to provide an improved roller adjusting mechanism for a folding machine wherein it is not necessary to manually adjust individual rollers. In this respect, a preferred embodiment of the invention will be described shortly; and, that preferred embodiment has additional advantages over a conventional fold-roller adjusting mechanism such as that described above. That is, when one of the preferred embodiment's movable rollers is adjusted in order to change the nip-space between two rollers, there is no change in the nip-space between that movable roller and another adjacent roller. Also, by reducing the number of movable rollers that are required, the illustrated embodiment eliminates the previously troublesome cumulative adjustment error; permits several of the rollers to be driven on their pitch diameters so as to increase efficiency; and, reduces power requirements and noise.
Additionally, as the speed of the above described conventional folder increases, the torques applied to the various rollers tend to urge them toward each other so that the high-speed nip-spaces become too small. Hence, it is customary for a skilled operator to provide oversize nip-spaces at low speeds so that the machine will operate properly at high speeds. The embodiment of the invention about to be described, however, does not have this disadvantage.
Still further, if narrow stock is folded in a conventional machine, it is difficult to properly adjust the nip spaces because they are preferably different on one side of the machine than on the other. Similarly, as a conventional machine's rollers wear, it is desirable to take such wear into account when the machine's nip spaces are adjusted for each different type of stock thickness and size that is run through the machine. As will be appreciated from the following description, however, the illustrated embodiment of the invention has an additional advantage of automatically adjusting the nip spaces to account for stock size and thickness and roller-wear.